Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0851184 (thinning)
 11,252 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Under basal conditions the echocardiographic findings in anginal patients (pts.) without previous myocardial infarction appears usually normal. Consequently, the usefulness of the ultrasounds evaluation in angina pectoris has been commonly considered poor and the utilization of this technique in coronary artery disease has been restricted to the detection of myocardial infarction in its acute phase or to its chronic mechanical alterations. The purpose of this study was to assess the possibility offered by M-mode echocardiography to detect changes caused by transient myocardial ischemia at rest in man, in view of the possible diagnostic application of this technique. The reported results were obtained from 25 ischemic attacks (13 spontaneous and 12 ergonovine induced) with ST segment elevation or pseudonormalization of a basally negative T wave at rest. The semiautomatic computerized analysis of echocardiograms continuously recorded during these attacks showed a reduction of motion and of systolic thickening, accompanied by a diastolic thinning of the wall involved by the ischemia. These changes occur very early: they appear few seconds before ECG changes and are accompanied by a reduction of contraction and relaxation dP/dt and precede the onset of chest pain; moreover, they are followed by an increase in left ventricular internal diameters. In conclusion M-mode echocardiography is a sensitive technique capable to detect transient myocardial ischemia in the course of spontaneous or induced angina with ST segment elevation or positivity of negative T wave. This approach could be helpful in the diagnostic evaluation of patients with atypical chest pain and/or aspecific ECG changes and it can be complementary to other non invasive techniques such dynamic ECG and nuclear cardiology techniques.
 ...
PMID:[Diagnosis of transient acute myocardial ischemia in man by M-mode echocardiography (author's transl)]. 732 34

Following prolonged ischemia, if not adequately reperfused, myocardium undergoes necrosis, scarring and thinning. The myocardium tends to dilate in the noninfarcted ventricular area, giving rise to ventricular remodelling. If the ischemic myocardium is adequately reperfused it can be saved and its temporarily depressed functions eventually be recuperated (viable myocardium). The extent of recovery of the postinfarction viable myocardium seems to affect ventricular remodelling. The integrity of the microcirculation of the non-contractile myocardium following prolonged ischemia is fundamental in maintaining a contractile reserve adequate enough for a functional recovery (myocardial viability). Protection of the microcirculation during ischemia-reperfusion is therefore of great importance for the role that the microcirculation plays in ensuring myocardial viability. Experimental studies and initial clinical observations showed that calcium-antagonists exert a beneficial effect in this respect. VAMI is a multicentre, randomized double-blind, placebo-controlled study whose aim is to ascertain the potentiality of verapamil in limiting regional functional damage in patients with acute myocardial infarction and undergoing early thrombolysis.
 ...
PMID:[Myocardial viability in acute myocardial infarction and verapamil]. 763 65

Nonlethal myocardial ischemia produces profound and long-lasting effects on regional ventricular function and metabolism (myocardial stunning) and protects against myocardial infarction from subsequent prolonged ischemia (ischemic preconditioning). Two-dimensional echocardiography (2DE) is an essential tool for quantitative analysis of regional and global left ventricular (LV) function during myocardial ischemia and reperfusion and the study of these phenomena. However, the inability to perform 2DE in the open-chest rat heart has seriously limited the use of this model. To investigate the effect of transient coronary occlusion on segmental wall motion and LV geometry, we employed a 20 MHz intravascular ultrasound catheter placed on the epicardial surface of the rat heart (n = 15) to yield 2DE images suitable for quantitative analysis. Three 2-minute left coronary occlusions were made, separated by 5 minutes of reperfusion, with imaging during occlusion and at 5 and 60 minutes of reperfusion. Ischemic and nonischemic wall thicknesses, LV cross-sectional area, estimated LV volume, and the fractional changes of these parameters were measured. In eight animals these values were also compared with necropsy measurements of wall thickness, LV cross-sectional area, and volume. LV and right ventricular structures were well visualized in short-axis cross-sectional images in all animals, and images suitable for quantitative analysis were obtained in 92% of the periods. Coronary occlusion caused immediate, marked LV cavitary expansion, which rapidly returned to normal by 5 minutes of reperfusion. Active systolic thickening of the anterior wall at baseline (47% +/- 3%) became passive thinning during occlusion (-6% +/- 2%) and recovered partially, to 30% +/- 3% at 5 minutes of reperfusion and 42% +/- 4% at 60 minutes (p < 0.0005 at 5 minutes of reperfusion vs baseline; p not significant at 60 minutes). Recovery of thickening after 5 minutes of reperfusion was not different after the first versus third occlusion (23% +/- 4% vs 30% +/- 3%; p = 0.19). Measurements made by 2DE correlated well with those made by necropsy, although wall thickness was slightly thicker by 2DE. We conclude that epicardial echocardiography with an intravascular ultrasound catheter provides quantifiable 2DE images in this model and yields accurate information on segmental wall thickening and ventricular geometry not available by other techniques. Left coronary occlusion in the rat is associated with marked global and segmental LV expansion, which rapidly reverses with reperfusion. Postischemic regional wall motion abnormalities are present after coronary occlusion as brief as 2 minutes and can be measured accurately. The effect of multiple brief occlusions is not cumulative.(ABSTRACT TRUNCATED AT 400 WORDS)
 ...
PMID:Quantitative two-dimensional echocardiographic assessment of regional wall motion during transient ischemia and reperfusion in the rat. 775 1

The purpose of this study was to assess the safety and histologic effects of radiofrequency thermal balloon angioplasty in the coronary vasculature of normal pigs. Radiofrequency thermal balloon angioplasty was performed in 30 coronary arteries of 16 nonatherosclerotic pigs. Heated inflations were performed at either 50 degrees, 60 degrees, or 70 degrees C for 30 or 60 seconds, and were compared with five nonheated inflations in five additional arteries. All balloon inflations were performed at 2 atm pressure with a balloon/vessel diameter ratio of 1.2 to 1. Heart rate, arterial pressure, and left ventricular pressure were monitored continuously for each animal. A 12-lead ECG, coronary angiography, and two-dimensional transthoracic echocardiography were performed before and 1 hour after each balloon inflation. Each animal was subsequently put to death for postmortem cardiac examination. Heated inflations were well tolerated in 28 of the 30 arteries without significant adverse effects. During one inflation, ventricular fibrillation occurred because of prolonged ischemia from an occlusive guiding catheter. In another artery, a heated inflation resulted in a dissection with a transient decrease in distal coronary flow. Histologic examination revealed a significant increase in wall thinning and elastic fiber straightening with heating at 70 degrees C for both 30 and 60 seconds, and a significant increase in intracoronary thrombus with heating at 70 degrees C for 60 seconds. Depth of periarterial myocardial heat necrosis paralleled the increase in temperature, with an average depth of 166 microns at 50 degrees C, 312 microns at 60 degrees C, and 1031 microns at 70 degrees C. In vivo, radiofrequency coronary angioplasty can be performed relatively safely without significant electrical, hemodynamic, or ischemic changes beyond those seen with conventional nonthermal angioplasty. The extent of heat-induced vessel wall thinning, elastic tissue straightening, intracoronary thrombus formation, and periarterial myocardial necrosis are all related to balloon temperature or duration of heating.
 ...
PMID:In vivo radiofrequency thermal balloon angioplasty of porcine coronary arteries: histologic effects and safety. 821 57

We investigated the temporal relationship of the emergence of biochemical abnormalities to the development of behavioral dysfunction to identify the central factors of ischemic neurological disorders in developing brains. To induce early ischemia, bilateral carotid artery occlusion (BCAO) was surgically performed on 21 cats at the second week of age. BCAO produces histopathological damage, including neuronal loss and thinning of white matter. 31P magnetic resonance spectroscopy was used to monitor brain oxidative metabolism, neuronal membrane growth, and myelination of the prefrontal cortex in the first 3 months. Neurological development was monitored by conducting 25 tests of reflex, motor, sensory, and integrated behavioral function. At 1 month, phosphodiester (PDE) levels, a component of membranes and myelin, were low in animals showing complete ligation. At 2 months, the growth of PDE was low (1/4 to 1/2 of normal) in BCAO animals, whereas normal animals demonstrated a 23% increase. Phosphocreatine (PCr) levels, indicated by PCr/ATP and PCr/inorganic phosphate ratios, were retarded at 2 months in completely ligated animals (1/4 of normal). Neurologically, the completely ligated animals showed retardation of general development. The retardation was most pronounced for integrative functions, including visual function, and became more pronounced later in development. The time course of emergence of the retardation generally coincided with emergence of abnormalities in phosphorous compounds. The simultaneous occurrence of several biochemical and functional abnormalities in development following early ischemic insult suggests a causal relationship between membrane and mitochondrial development and neurological function.
 ...
PMID:Consequences of reduced cerebral blood flow in brain development. II. Retardation of neurological outcome and phosphorus metabolism. 828 31

In recent years, the right gastroepiploic artery has been attracting attention as a second reliable arterial graft for clinical application. In this study we measured the postoperative graft diameter of the right gastroepiploic artery and demonstrated the postoperative "thinning down" phenomenon of the right gastroepiploic artery graft. We report on coronary revascularization with the right gastroepiploic artery in 55 cases from December 1989 to July 1991. The properties of right gastroepiploic artery grafts were comparatively examined with the use of postoperative angiographic findings when possible. The results revealed that the patency ratio of right gastroepiploic artery grafts was satisfactory, with an average diameter of 2.1 mm (range 1.2 to 3.5 mm). "String sign" was not observed in these cases, but thinning down was noted in four cases. The thinning down phenomenon of the right gastroepiploic artery had previously been defined as a graft diameter no greater than that of a 5F catheter, with ineffective graft flow; it was termed slender sign. The development of slender sign is caused by good native coronary flow, narrowing of the perfused region, and poor runoff. Three cases of slender sign caused by good native flow had no signs of ischemia in the perfused regions, which was indicative of sufficient blood supply to the myocardium. The long-term patency ratio of right gastroepiploic artery grafts should be evaluated further.
 ...
PMID:Effect of coronary revascularization with the right gastroepiploic artery. Comparative examination of angiographic findings in the early postoperative period. 832 Sep 93

Previous studies have demonstrated that transforming growth factor-beta (TGF-beta) can accelerate wound healing, inhibit free radical formation and limit myocardial ischemia/reperfusion injury in a variety of experimental models. However, it is unknown whether exogenous TGF-beta 1 can attenuate the prolonged contractile dysfunction that is observed after a brief, reversible ischemic insult (myocardial stunning). Thus, open-chest dogs undergoing a 15-min left anterior descending coronary artery occlusion and 4 h of reperfusion were given TGF-beta 1 as an intravenous bolus (250 micrograms) at 24 h and again at 1 h before coronary occlusion (n = 5). Control dogs (n = 7) received equivalent amounts of vehicle. The two groups were similar with respect to occluded bed size, collateral blood flow and rate-pressure product. Fundamental physiological parameters, such as body temperature, arterial pH, PO2 and hematocrit, were within normal limits throughout the experiment. In control dogs, regional myocardial function (assessed as systolic thickening fraction) remained depressed throughout the 4 h reperfusion period, indicating severe myocardial stunning. TGF-beta 1 did not produce any significant improvement in the recovery of regional function; 4 h after reperfusion, paradoxical systolic thinning was still present in both treated and control groups, with thickening fraction being -22.5 +/- 6.1% and -31.0 +/- 5.3% of baseline, respectively (P = N.S.). These results demonstrate that a large dose of TGF-beta 1 given before ischemia fails to attenuate myocardial stunning in the open-chest dog, suggesting that this growth factor does not exert protective effects in the setting of reversible myocardial ischemia/reperfusion injury.
 ...
PMID:Effect of transforming growth factor-beta 1 on myocardial stunning in the intact dog. 834 Sep 31

Previous investigators have hypothesized that myocardial "stunning" may result either from a primary impairment in excitation or from electromechanical dissociation. Thrombolytic therapy and angioplasty have increased the importance of understanding the electrophysiologic effects of brief ischemia followed by reperfusion. We investigated the electrophysiologic properties of mechanically dysfunctional stunned myocardium in 18 dogs anesthetized with pentobarbital (30 mg/kg, intravenously administered). After thoracotomy, the proximal anterior descending coronary artery was occluded for 15 minutes, which was followed by 20 minutes of reperfusion. At baseline, peak ischemia, and 20 minutes of reperfusion, local electrogram durations, activation times, and refractory periods were measured from 12 standardized sites within the ischemic and border zones. Echocardiographic percentage of systolic wall thickening confirmed normal preischemic and markedly reduced postischemic function in the investigated region. Despite the marked electrophysiologic abnormalities observed in the ischemic zone during ischemia, mean electrogram duration, calculated conduction velocity, and mean effective refractory period after 20 minutes of reperfusion had returned almost to baseline values 39.2 +/- 11.5 msec versus 37.2 +/- 12.1 msec, 0.65 +/- 0.15 m/sec versus 0.68 +/- 0.15 m/sec, and 134 +/- 14 msec versus 131 +/- 8 msec, respectively. Corresponding mean values within the ischemic border zone were similarly close to baseline values after reperfusion. There was no significant difference in local heterogeneity (coefficient of variation) within the ischemic or border zone after reperfusion versus baseline values. Although the postischemic electrophysiologic status returned to normal, systolic thinning and dyskinesis persisted in the region of measurement. The contractile dysfunction that results from reperfusion-induced injury can thus occur in the setting of apparent excitation-contraction uncoupling.
 ...
PMID:Electrophysiologic recovery in postischemic, stunned myocardium despite persistent systolic dysfunction. 841 23

Miniature swine were used to study the effect of cervical fracture on femoral head blood flow. Laser Doppler flowmetry was used to evaluate femoral head blood flow before and after the fracture, after internal fixation with or without compression, and 8 weeks post-fracture. Fluorescent bone-labeling was performed at 2, 4 and 6 weeks post-fracture. Femoral head blood flow decreased to 40 percent of baseline following fracture, partly from the disruption of venous drainage. Histologically, all femoral heads showed some degree of trabecular thinning, microfracture, and neovascularization when compared with controls. Analyses of the laser Doppler flowmetry data, fluorescent label histology, microradiography and bone densitometry indicated that late (4-6 weeks) revascularization produces severe trabecular mechanical weakening and resultant femoral head collapse. Femoral head ischemia following fracture probably falls along a continuum, with only the more severe cases proceeding to mechanical collapse. Femoral neck fractures in the minipig produce femoral head necrosis of a severity and incidence which closely parallels that of the human population; thus, the minipig is a useful model for further study of complications following femoral neck fracture in humans.
 ...
PMID:The effect of fracture on femoral head blood flow. Osteonecrosis and revascularization studied in miniature swine. 849 86

Collagen which is present in the myocardium in relatively small amounts is the most abundant structural protein of the connective tissue network. Its structural organization consists of a complex weave of collagen fibers that surrounds and interconnects myocytes, groups of myocytes, muscle fibers and muscle bundles. The conformation of interstitial fibrillar collagen makes it highly resistant to degradation by all proteinases other than specific collagenases. In hearts with myocardial damage secondary to myocardial infarction, chronic ischemia, inflammation, or cardiomyopathy, a complex sequence of compensatory events occur that eventually result in an adverse left ventricular remodeling. This continual state of remodeling is characterized by persistent collagenase activity, fibrillar collagen degradation, and progressive myocyte loss. The net effect is a shift in the balance between collagen synthesis and degradation which leads to an inadequate fibrillar collagen matrix, progressive ventricular dilatation and sphericalization with wall thinning and eventual congestive heart failure.
 ...
PMID:Ventricular remodeling in heart failure: the role of myocardial collagen. 854 Apr 1


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>